I bought a NEW SONY USB flash device from a trusted store. I plugged it in. Then, it need to be formatted before use. I was formatting the USB, and it goes smoothly. But at the end, it sas "windows is unable to complete format" or something like that.

What should I do? I need an answer ASAP

Return it to the trusted store :)

Go to command prompt and type the drive in which it is.
Initially the command prompt will be like this

C:\<Users>\<....>\
Enter the drive in which your USB is. For example if your USB is in F drive, then typr F:, the control comes to the F drive....Now type format F: and follow instructions. All the Best. :)

I bought a NEW SONY USB flash device from a trusted store. I plugged it in. Then, it need to be formatted before use. I was formatting the USB, and it goes smoothly. But at the end, it sas "windows is unable to complete format" or something like that.

What should I do? I need an answer ASAP

Maybe it is a compatibility-related problem, as I recently have experienced using USB-flash-drivers. If you have the USB-drive (2.0) connected to a 3.0 USB-port, it may not work properly. In order to make it work, use it with a 2.0 port. Not sure if that is your problem, but try connecting to a 2.0, to make sure it's not hardware-related :)

i have already facing the same problem and looking forward the solution.

i have already facing the same problem and looking forward the solution.

you forgot your link .lol

Thanks for all of u i return this USB to that store :)

haha,you want an answer then returned it,why not return it in the first place?